This introduces three tests: 1) Sanity check soft dirty basic semantics: allocate area, clean, dirty, check if the SD bit flipped. 2) Check VMA reuse: validate the VM_SOFTDIRTY usage 3) Check soft-dirty on huge pages
This was motivated by Will Deacon's fix commit 912efa17e512 ("mm: proc: Invalidate TLB after clearing soft-dirty page state"). I was tracking the same issue that he fixed, and this test would have caught it.
Cc: Will Deacon will@kernel.org Signed-off-by: Gabriel Krisman Bertazi krisman@collabora.com Signed-off-by: Muhammad Usama Anjum usama.anjum@collabora.com --- Changes in V3: Move test to selftests/vm Use kselftest macros Minor updates to make code more maintainable Add configurations in config file
Tests of soft dirty bit in this patch and in selftest/vm/madv_populate.c are non-overlapping.
V2 of this patch: https://lore.kernel.org/lkml/20210603151518.2437813-1-krisman@collabora.com/ --- tools/testing/selftests/vm/.gitignore | 1 + tools/testing/selftests/vm/Makefile | 1 + tools/testing/selftests/vm/config | 2 + tools/testing/selftests/vm/soft-dirty.c | 238 ++++++++++++++++++++++++ 4 files changed, 242 insertions(+) create mode 100644 tools/testing/selftests/vm/soft-dirty.c
diff --git a/tools/testing/selftests/vm/.gitignore b/tools/testing/selftests/vm/.gitignore index d7507f3c7c76..3cb4fa771ec2 100644 --- a/tools/testing/selftests/vm/.gitignore +++ b/tools/testing/selftests/vm/.gitignore @@ -29,5 +29,6 @@ write_to_hugetlbfs hmm-tests memfd_secret local_config.* +soft-dirty split_huge_page_test ksm_tests diff --git a/tools/testing/selftests/vm/Makefile b/tools/testing/selftests/vm/Makefile index 5e43f072f5b7..de9b13d018c3 100644 --- a/tools/testing/selftests/vm/Makefile +++ b/tools/testing/selftests/vm/Makefile @@ -47,6 +47,7 @@ TEST_GEN_FILES += on-fault-limit TEST_GEN_FILES += thuge-gen TEST_GEN_FILES += transhuge-stress TEST_GEN_FILES += userfaultfd +TEST_GEN_FILES += soft-dirty TEST_GEN_FILES += split_huge_page_test TEST_GEN_FILES += ksm_tests
diff --git a/tools/testing/selftests/vm/config b/tools/testing/selftests/vm/config index 60e82da0de85..be087c4bc396 100644 --- a/tools/testing/selftests/vm/config +++ b/tools/testing/selftests/vm/config @@ -4,3 +4,5 @@ CONFIG_TEST_VMALLOC=m CONFIG_DEVICE_PRIVATE=y CONFIG_TEST_HMM=m CONFIG_GUP_TEST=y +CONFIG_TRANSPARENT_HUGEPAGE=y +CONFIG_MEM_SOFT_DIRTY=y diff --git a/tools/testing/selftests/vm/soft-dirty.c b/tools/testing/selftests/vm/soft-dirty.c new file mode 100644 index 000000000000..f56c215e0ece --- /dev/null +++ b/tools/testing/selftests/vm/soft-dirty.c @@ -0,0 +1,238 @@ +// SPDX-License-Identifier: GPL-2.0 +#include <stdio.h> +#include <string.h> +#include <stdbool.h> +#include <fcntl.h> +#include <stdint.h> +#include <malloc.h> +#include <sys/mman.h> +#include "../kselftest.h" + +#define PAGEMAP_PATH "/proc/self/pagemap" +#define CLEAR_REFS_PATH "/proc/self/clear_refs" +#define SMAP_PATH "/proc/self/smaps" +#define PMD_SIZE_PATH "/sys/kernel/mm/transparent_hugepage/hpage_pmd_size" +#define MAX_LINE_LENGTH 512 +#define TEST_ITERATIONS 10000 +#define PAGE_NUM_TO_TEST 2 + +int clear_refs; +int pagemap; + +int pagesize; +int mmap_size; /* Size of test region */ + +static void clear_all_refs(void) +{ + const char *ctrl = "4"; + + if (write(clear_refs, ctrl, strlen(ctrl)) != strlen(ctrl)) + ksft_exit_fail_msg("%s: failed to clear references\n", __func__); +} + +static void touch_page(char *map, int n) +{ + map[(pagesize * n) + 1]++; +} + +static int check_page(char *start, int page_num, int clear) +{ + unsigned long pfn = (unsigned long)start / pagesize; + uint64_t entry; + int ret; + + ret = pread(pagemap, &entry, sizeof(entry), (pfn + page_num) * sizeof(entry)); + if (ret != sizeof(entry)) + ksft_exit_fail_msg("reading pagemap failed\n"); + if (clear) + clear_all_refs(); + + return ((entry >> 55) & 1); +} + +static void test_simple(void) +{ + int i; + char *map; + + map = aligned_alloc(pagesize, mmap_size); + if (!map) + ksft_exit_fail_msg("mmap failed\n"); + + clear_all_refs(); + + for (i = 0 ; i < TEST_ITERATIONS; i++) { + if (check_page(map, PAGE_NUM_TO_TEST, 1) == 1) { + ksft_print_msg("dirty bit was 1, but should be 0 (i=%d)\n", i); + break; + } + + touch_page(map, 2); + + if (check_page(map, PAGE_NUM_TO_TEST, 1) == 0) { + ksft_print_msg("dirty bit was 0, but should be 1 (i=%d)\n", i); + break; + } + + } + free(map); + + ksft_test_result(i == TEST_ITERATIONS, "Test %s\n", __func__); +} + +static void test_vma_reuse(void) +{ + char *map, *map2; + + map = (char *) 0x900000000000; + map = mmap(map, mmap_size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON, -1, 0); + if (map == MAP_FAILED) + ksft_exit_fail_msg("mmap failed"); + + clear_all_refs(); + touch_page(map, PAGE_NUM_TO_TEST); + + munmap(map, mmap_size); + map2 = mmap(map, mmap_size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON, -1, 0); + if (map2 == MAP_FAILED) + ksft_exit_fail_msg("mmap failed"); + + ksft_test_result(map == map2, "Test %s reused memory location\n", __func__); + + ksft_test_result(check_page(map, PAGE_NUM_TO_TEST, 1) != 0, + "Test %s dirty bit of previous page\n", __func__); + + munmap(map2, mmap_size); +} + +/* + * read_pmd_pagesize(), check_for_pattern() and check_huge() adapted + * from 'tools/testing/selftest/vm/split_huge_page_test.c' + */ +static uint64_t read_pmd_pagesize(void) +{ + int fd; + char buf[20]; + ssize_t num_read; + + fd = open(PMD_SIZE_PATH, O_RDONLY); + if (fd == -1) + ksft_exit_fail_msg("Open hpage_pmd_size failed\n"); + + num_read = read(fd, buf, 19); + if (num_read < 1) { + close(fd); + ksft_exit_fail_msg("Read hpage_pmd_size failed\n"); + } + buf[num_read] = '\0'; + close(fd); + + return strtoul(buf, NULL, 10); +} + +static bool check_for_pattern(FILE *fp, const char *pattern, char *buf) +{ + while (fgets(buf, MAX_LINE_LENGTH, fp) != NULL) { + if (!strncmp(buf, pattern, strlen(pattern))) + return true; + } + return false; +} + +static uint64_t check_huge(void *addr) +{ + uint64_t thp = 0; + int ret; + FILE *fp; + char buffer[MAX_LINE_LENGTH]; + char addr_pattern[MAX_LINE_LENGTH]; + + ret = snprintf(addr_pattern, MAX_LINE_LENGTH, "%08lx-", + (unsigned long) addr); + if (ret >= MAX_LINE_LENGTH) + ksft_print_msg("%s: Pattern is too long\n", __func__); + + fp = fopen(SMAP_PATH, "r"); + if (!fp) + ksft_print_msg("%s: Failed to open file %s\n", __func__, SMAP_PATH); + + if (!check_for_pattern(fp, addr_pattern, buffer)) + goto err_out; + + /* + * Fetch the AnonHugePages: in the same block and check the number of + * hugepages. + */ + if (!check_for_pattern(fp, "AnonHugePages:", buffer)) + goto err_out; + + if (sscanf(buffer, "AnonHugePages:%10ld kB", &thp) != 1) + ksft_print_msg("Reading smap error\n"); + +err_out: + fclose(fp); + + return thp; +} + +static void test_hugepage(void) +{ + char *map; + int i, ret; + size_t hpage_len = read_pmd_pagesize(); + + map = memalign(hpage_len, hpage_len); + if (!map) + ksft_exit_fail_msg("memalign failed\n"); + + ret = madvise(map, hpage_len, MADV_HUGEPAGE); + if (ret) + ksft_exit_fail_msg("madvise failed %d\n", ret); + + for (i = 0; i < hpage_len; i++) + map[i] = (char)i; + + ksft_test_result(check_huge(map), "Test %s huge page allocation\n", __func__); + + clear_all_refs(); + for (i = 0 ; i < TEST_ITERATIONS ; i++) { + if (check_page(map, PAGE_NUM_TO_TEST, 1) == 1) { + ksft_print_msg("dirty bit was 1, but should be 0 (i=%d)\n", i); + break; + } + + touch_page(map, PAGE_NUM_TO_TEST); + + if (check_page(map, PAGE_NUM_TO_TEST, 1) == 0) { + ksft_print_msg("dirty bit was 0, but should be 1 (i=%d)\n", i); + break; + } + } + + ksft_test_result(i == TEST_ITERATIONS, "Test %s dirty bit\n", __func__); + + munmap(map, mmap_size); +} + +int main(int argc, char **argv) +{ + ksft_print_header(); + ksft_set_plan(5); + + pagemap = open(PAGEMAP_PATH, O_RDONLY); + if (pagemap < 0) + ksft_exit_fail_msg("Failed to open %s\n", PAGEMAP_PATH); + + clear_refs = open(CLEAR_REFS_PATH, O_WRONLY); + if (clear_refs < 0) + ksft_exit_fail_msg("Failed to open %s\n", CLEAR_REFS_PATH); + + pagesize = getpagesize(); + mmap_size = 10 * pagesize; + + test_simple(); + test_vma_reuse(); + test_hugepage(); + + return ksft_exit_pass(); +}